In current Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, a User Equipment device (UE) sends a Scheduling Request (SR) to an enhanced or evolved Node B (eNB) when the UE wishes to transmit data in the uplink. The SR is accompanied with a Buffer Status Report (BSR). Based on the BSR, the eNB will give the UE an uplink grant with a number of Physical Resource Blocks (PRBs) and a Modulation and Coding Scheme (MCS) with which the UE should transmit its data in the uplink. The number of PRBs and the MCS correspond to a defined Transport Block Size (TBS). Thus, the selection of the number of PRBs and the MCS is oftentimes referred to as TBS selection and is done for a given target Block Error Rate (BLER).
For mobile broadband services, the target BLER is relatively high (e.g., 10%) since it is more beneficial from a systems perspective to keep interference levels in check and rely on Hybrid Automatic Repeat Request (HARQ) retransmissions if needed. Further, since there are usually free resources in the network, the eNB scheduler oftentimes gives the UE an uplink grant having a TBS that is substantially larger than that which is needed for the uplink buffer size reported in the BSR. This is beneficial because more data may be added to the uplink buffer between the time at which the UE transmits the BSR and the time at which the UE is allowed to transmit. If the TBS for the uplink grant is larger than the uplink buffer size when the UE transmits, the UE must include padding, or dummy, bits in the uplink transmission in order to match the TBS of the uplink grant. The UE is obligated to transmit exactly as dictated by the eNB scheduler.
In addition to Mobile Broadband (MBB) services, Fifth Generation (5G) systems will support Machine Type Communication (MTC). MTC will be both massive MTC, which focuses on very large numbers of simple devices transmitting small data payloads (sensors, actuators, etc.), and critical MTC, which focuses on low latency applications (e.g., industrial control). In both cases, the majority of devices are battery operated and frequent charging is not feasible. For massive MTC, a battery life of around ten years is often mentioned as a target, and this puts high requirements on UE power consumption.
Patent Cooperation Treaty (PCT) Patent Application Publication No. WO 2014/113243 A2, entitled “Channel State Information and Adaptive Modulation and Coding Design for Long-Term Evolution Machine Type Communications,” describes systems and methods for minimizing the number of Channel State Information (CSI) transmissions from a MTC UE to an eNB, which in turn reduces power consumption by the MTC UE.
While WO 2014/113243 A2 teaches reducing power consumption by a MTC UE by decreasing the amount of CSI transmissions, there remains a need for systems and methods reducing power consumption and/or decreasing latency of a MTC device.